In the light of the recent drive towards reduced CO2 emissions, there has been an increasing demand for systems for generating power using forms of natural energy such as wind power and water power. Apart from such large-scale, natural energy-utilizing systems, there has also been a demand for power generation systems allowing the comparatively small amounts of electrical power needed in the home to be generated within the household. One example thereof is the home fuel cell, for which a variety of proposals have been made, some of which have already been put to practical use (see, for example, patent documents 1 and 2).